Date:         Wed, 3 Jan 1996 12:25:01 -0500
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         SyncroHead@aol.com
Subject:      Re: 89 syncro, binds in tight turning

In a message dated 96-01-03 01:38:49 EST, steveh@emu.com (Steve Hoge) writes:

>> My friend has a 89 syncro, just purchased. When turning tight. The wheels
>> bind and have a lurching sensation. The characteristics seem like the rear
>> diff is locked. VW machanic say the CV's are fine. He said it is a normal
>> function of a Syncro. 
>
>It *is* normal for the Syncro to feel a little funny when tight turning,
>but I don't get the lurching or binding; at certain speeds I seem to get
>"pulled through" the turn, which is actually a positive handling
>characteristic.
>
>The different steering sensation occurs since the circles tracked by the
>front wheels are appreciably larger than those tracked by the rear, so
>there is a front/rear rotation-rate difference which the viscous
>coupling "doesn't like". However, this represents a "front slip/rear
>traction" situation, the reverse of the normal 4W-engaged scenario, and
>I have been curious about whether the viscous coupling would engage in
>this case (Syncronauts help me out here.)  This would be somewhat
>related to the question: do you get 4WD in reverse? (since the torque on
>the viscous coupler from the drive shaft is also in the opposite
>direction.)
>
>I have been warned by mechanics *not* to make tight U-turns in a Syncro
>(do a 3-pt instead) because of these considerations...is it just an old
>wive's tale that this is hard on the front drive?
>
>Of course, the symptoms described also sound alot like a locked
>differential - it should be pretty easy to determine whether the rear
>diff-lock is on (if you have one - if so, make sure the front display
>light, which gives positive feedback, isn't burnt out) - but a *front*
>differential which has locked up :-( might give similar symptoms, along
>with other steering anomalies.
>
>Steve Hoge

I would describe the feeling I get during U-turns in my Syncro as a "slight
binding sensation".  As Steve describes above, the tires are turning at
different rates and the function of the viscous coupling comes into play.  I
wouldn't describe this as something that the coupling "doesn't like", just
normal operation.  The coupling will operate in reverse the same way as it
does going forward.  When one shaft starts turning at a different speed than
the other, the viscous silicon fluid acts to bind them together and bring
them back to equal speed.  I don't think that U-turns do anything to the
coupling that it wouldn't nomally see on a traction poor surface.

Jim Davis
87 Syncro
88 Wolfsburg